Text File Operations & amp; user and user group management, text file operations

Operations on text files & user and user group management, and operations on text files

Text File Operations

#Input redirection

Tr 'a-Z'

Hello

HELLO

World

WORLD

After redirection

Tr 'a-Z' <file

HELLO WORLD

#Format the input content to a file:

 

#Standard input, standard output, and standard errors

Standard input 0 (read only on keyboard), standard output 1, and standard error 2 (write only on display)

For example, the passwd file contains standard output 1 and standard error 2.

 

Only display standard error 2 to display, standard output 1 Write passwd. OK

 

Only display standard output 1 to the display, standard error 2 Write passwd. err

 

View the written files passwd. OK and passwd. err.

 

The standard output 1 and standard error 2 are both written to passwd. OK (Note: directly write ">", append to the original file and add "> ")

 

#Pipeline "|"

Meaning: The correct output of the previous command is used as the standard input of the command after the pipeline operator;

 

Here, only two entries are entered correctly.

Convert a standard error to a standard output: "2> & 1"

 

# Tee

Saving the output as a file does not affect the display of the display (Example 3 ))

#Exercise:

1 ).

2) display line 15-18 of the/etc/passwd file;

3). The display/Bind file contains a large master file and saved to the bin_upper_file.txt file,

The statistics are displayed on the screen;

 

User and User Group Management

#User Management

User File:/etc/passwd

User: passwd: uid: gid: user Description: user's home directory: shell Type

Command: useradd usermod id (userdel-r username)

#User Group Management

User group file:/etc/group

Groupname: passwd: gid: group member

Command: groupadd (-g) groupmod groupdel

#Manage user passwords

User Group file:/etc/shadow

Command: passwd chage

#Grant sudo permissions to users

Use sudo useradd hello

#Exercise:

 

The creation result is as follows:

Passwd and chage commands can be used for modification.

The result is as follows: